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cbigham's avatar
cbigham
Explorer III
Dec 30, 2013

vehicle speed sensor- cat C7-allison trans combo

Got a funmover 39c on an f750 cat c7 chassis with a speedometer going wacko....one second at 0, then 90, bouncing around. Would be easier to service if the engine wasn't cutting out thinking its over ...
Class A
gatorcq's avatar
gatorcq
Explorer
Dec 30, 2013
The engine speed signals comes from a sensor located on the engine. The speedometer signal to the dash is driven from the electronic control unit(CAT).

If it is jumping around, you may have a bad sensor or connection. For the record there is a primary and secondary sensor.

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